with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a single peak
with a duration of about 20 sec. The peak count rate
was ~1200 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 02:45:53.4 UT, 133.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 129.00074, 54.34876 which is equivalent
to:

RA(J2000) = 08h 36m 00.18s
Dec(J2000) = +54d 20' 55.5"

with an uncertainty of 3.5 arcseconds (radius, 90% containment). This
location is 91 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (4.13 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 1.2
(+1.30/-1.19) x 10^21 cm^-2 (90% confidence).
No UVOT data are available at this time.
Burst Advocate for this burst is M. Stamatikos (Michael.Stamatikos-1 AT nasa.gov).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)

GCN Circular #20088
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:
Using promptly downlinked XRT event data for GRB 161022A, we find an
enhanced XRT position of the afterglow: RA, Dec: 129.0018, 54.3490
which is equivalent to:

RA (J2000) = 08 36 00.44
Dec (J2000) = +54 20 56.3

with an uncertainty of 2.0 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/718655.
Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.

GCN Circular #20089
Klotz A., Turpin D., Atteia J.L. (CNRS-OMP-IRAP),
Boer, M., Laugier, R. (CNRS-ARTEMIS),
Gendre B. (UVI - Etelman Obs.) report:
We imaged the field of GRB 161022A detected by SWIFT
(trigger 718655) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.
The observations started 71s after the GRB trigger
(17s after the notice). The elevation of the field increased
from 56 degrees above horizon and weather conditions
were excellents.
The first image is trailed with a duration of 60.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT with a limiting magnitude of:
t0+71.2s to t0+131.2s : Rlim = 17.4
The second image is 30.0s exposure in tracking mode:
t0+146.3s to t0+176.3s : Rlim = 18.5
We co-added a series of exposures:
t0+146.3s to t0+442.9s : Rlim = 19.0
No more OT detection until t0+6800s at Rlim = 19.0.
Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.

with an uncertainty of 2.0 arcsec (radius, 90% confidence).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.46 (+0.13, -0.11).
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.70 (+0.16, -0.07). The
best-fitting absorption column is consistent with the Galactic value
of 4.1 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum is 3.8 x 10^-11 (4.0 x 10^-11) erg cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:

If the light curve continues to decay with a power-law decay index of
1.46, the count rate at T+24 hours will be 1.5 x 10^-4 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.6 x
10^-15 (5.9 x 10^-15) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00718655.
This circular is an official product of the Swift-XRT team.

with an uncertainty of 1.4 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).
This circular was automatically generated, and is an official product of the
Swift-XRT team.

GCN Circular #20095
D. Malesani (DARK/NBI and DTU Space) and J. Prieto-Arranz (IAC) report
on behalf of a larger collaboration:
We observed the field of GRB 161022A (Stamatikos et al., GCN 20087)
using the Nordic Optical Telescope (NOT) equipped with the AlFOSC
imaging camera. Observations started on 2016 Oct 22.161 UT, 68.5 min
after the GRB, and consisted of 2x300 s exposures in the SDSS r band.
Observations were affected by adverse weather conditions.
Within or in the proximity of the XRT error circle (Evans, GCN 20088),
at a mid time of 73.9 min after the GRB trigger, we detect no new
sources down to a limiting magnitude r > 22 (AB), calibrated against
nearby SDSS stars.

GCN Circular #20096
O.J. Roberts (UCD) reports on behalf of the Fermi GBM Team:
At 02:43:45.92 UT on October 22nd, 2016, the Fermi Gamma-Ray
Burst Monitor triggered and located GRB 161022A
(trigger 498797029/161022114), which was also detected by Swift
(Stamatikos et al., GCN 20087). The GBM on-ground location is
consistent with the Swift position. The angle from the Fermi LAT
boresight is 131 degrees.
The GBM light curve shows a weak, FRED-like peak with a duration
(T90) of about 19 s (50-300 keV). The time-averaged spectrum
from T0-6.1 s to T0+11.3 s is adequately fit by a power law function
with an exponential high-energy cutoff. The power law index is
-0.59 +/- 0.37 and the cutoff energy, parameterized as Epeak,
is 155.7 +/- 33.2 keV
The event fluence (10-1000 keV) in this time interval is
(1.65 +/- 0.24)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-1.3 s in the 10-1000keV band is 2.5 +/- 0.4 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog.

with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 14%.
The mask-weighted light curve shows a few overlapping peaks starting at ~T-1 sec,
peaking at ~T+2 sec, an ending at ~T+15 sec.
T90 (15-350 keV) is 7.3 +- 1.0 sec (estimated error including systematics).
The time-averaged spectrum from T+0.53 to T+8.24 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.14 +- 0.21. The fluence in the 15-150 keV band is 7.5 +- 1.0 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+2.13 sec in the 15-150 keV band
is 1.6 +- 0.4 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/718655/BA/